How do I update Geth to the latest version when I am using Ethereum Wallet on a Mac OSX?
It is not prompting me for an update to Geth as I skipped it the first time Ethereum Wallet was opened after an update and I need to do it now.
I discovered that the simple solution is to go to the top toolbar in the Ethereum Wallet and select 'Ethereum Wallet' and then select 'Check for Ethereum node updates' in the drop down list. It checks for the latest Geth and then asks whether you want to update to that version.
This method allows you to continue downloading the blockchain from your current point, without deleting previous downloads, which saves a lot of time.
Ethererum Wallet for Mac OSX 0.9.3 will currently only give the option to go to Geth version 1.7.2, although there is a version of Geth 1.7.3 available. There is an open issue on Github to resolve this.
A fix for blocks stuck at 4,370,000, the point of the Byzantium hard fork, was to update Geth by this method. Even though Ethereum Wallet is updated to a post-hard-fork version, Geth needs to update to a post-hard-fork version too, so the blocks that are downloaded continue with the current chain.
You can check your block number agrees with https://etherscan.io/ to confirm that your Ethereum Wallet is up to date.
You can delete the .ethereum/ folder (it is for linux, for mac os I think it is /lib/ethereum/) or something like that. It will be like the first launch (backup your keystore before do that).